1. update clientset, deepcopy using code-generator

2. add a dummy file tools.go to force "go mod vendor" to see
code-generator as dependencies
3. add a script to update CRD
4. add a README to document CRD updating steps
run go mod tidy
update README

vendor/k8s.io/code-generator/cmd/openapi-gen/main.go

@@ -0,0 +1,57 @@
+/*
+Copyright 2018 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// This package generates openAPI definition file to be used in open API spec generation on API servers. To generate
+// definition for a specific type or package add "+k8s:openapi-gen=true" tag to the type/package comment lines. To
+// exclude a type from a tagged package, add "+k8s:openapi-gen=false" tag to the type comment lines.
+
+package main
+
+import (
+	"flag"
+	"log"
+
+	generatorargs "k8s.io/kube-openapi/cmd/openapi-gen/args"
+	"k8s.io/kube-openapi/pkg/generators"
+
+	"github.com/spf13/pflag"
+
+	"k8s.io/klog"
+)
+
+func main() {
+	klog.InitFlags(nil)
+	genericArgs, customArgs := generatorargs.NewDefaults()
+
+	genericArgs.AddFlags(pflag.CommandLine)
+	customArgs.AddFlags(pflag.CommandLine)
+	flag.Set("logtostderr", "true")
+	pflag.CommandLine.AddGoFlagSet(flag.CommandLine)
+	pflag.Parse()
+
+	if err := generatorargs.Validate(genericArgs); err != nil {
+		log.Fatalf("Arguments validation error: %v", err)
+	}
+
+	// Generates the code for the OpenAPIDefinitions.
+	if err := genericArgs.Execute(
+		generators.NameSystems(),
+		generators.DefaultNameSystem(),
+		generators.Packages,
+	); err != nil {
+		log.Fatalf("OpenAPI code generation error: %v", err)
+	}
+}